- Preheat oven to 350°F. Stir flour, baking powder, ginger, baking soda and cinnamon in medium bowl.
- Beat butter, sugar and molasses in large bowl.
- Mix in egg.
- Add flour mixture alternately with water, stirring just until blended.
- Pour into greased 9-inch square baking pan.
- Bake 40 minutes.
- Cool in pan on wire rack 10 minutes.
- Invert cake onto wire rack to cool completely.
- Serve with whipped cream, if desired.